1. Field of the Invention
The present invention relates to a silver halide photographic light-sensitive material containing a novel non-color forming coupling compound capable of releasing a development inhibitor.
2. Description of the Prior Art
It is known that a compound capable of releasing a development inhibitor can be used by addition of such a compound to a photographic light-sensitive material or a processing solution. The use of such a compound provides an image having improved quality where the compound imagewise releases a development inhibitor with a moderate development inhibiting action at a certain step between exposure and development of a photographic light-sensitive material. On the other hand, when such a compound releases a development inhibitor capable of completely inhibiting development, the compound provides a reversal image of improved quality. Such compounds can be employed for preparing both black-and-white light-sensitive materials and color light-sensitive materials, and have found a wide variety of applications, for example, to improve the quality of an image which a conventional color light-sensitive material provides, in application to light-sensitive materials for special uses such as light-sensitive materials with a wide latitude or for forming double images, for the formation of reversal images, to provide a masking effect by the combined use of a fogged emulsion and such a compound, for the production of color diffusion transfer photographic materials and color direct positive photographic light-sensitive materials and the like.
It has been found by a number of researchers that compounds of this type can contribute to an improvement in image quality because a development inhibitor is released imagewise by the reaction of the oxidation product of a color developing agent with a compound of this type when a multi-layer color light-sensitive material containing such a compound in a light-sensitive layer thereof is exposed to light and then developed with a color developer to exert effects on layers adjacent the light-sensitive layer. That is, the development inhibitor can provide not only a so-called intralayer effect to achieve controlled contrast, reduced graininess and improved sharpness of the developed image, and the like, but also a so-called interlayer effect such as preventing color turbidity and improved color purity due to a masking effect, and the like. Typical development inhibitor releasing compounds of this type include the so-called DIR couplers, the active position of which contains a group which exhibits a development inhibiting action when it is split from the active position of the coupler compound. DIR couplers form dyes by coupling with the oxidation product of a color developing agent and release a development inhibitor. Compounds such as those disclosed in U.S. Pat. Nos. 3,227,554, 3,701,783, 3,615,506, 3,617,291 and the like are known as DIR couplers. DIR couplers are used for the purpose of controlling the image tone, reducing the graininess of the image, improving color reproduction and the like, as is well known from the disclosure in the above described patents.
However, in many cases, DIR couplers of this type do not exert the desired inhibiting effect because the dye yield upon development adversely affects color reproduction unless an appropriate type of a coupler residue and an appropriate amount of the coupler are precisely chosen and convenient selection of a coupler residue for color reproduction restricts the permissible reactivity of the oxidation product of the color developing agent and the coupler. In addition, DIR couplers of this type have various disadvantages such as poor stability against ageing, they often exhibit a desensitization effect, they produce mottle resulting from contamination of the developer solution and the like.
The so-called non-color forming type of coupling compounds were developed with the intention of eliminating these disadvantages, which coupling compounds yield essentially colorless products or colored products whose colors are changed, however, and become essentially colorless in the course of photographic treatment upon coupling with the oxidation product of a color developing agent, and also yield a development inhibitor at the same time. Known compounds of this type include compounds such as are disclosed in German Patent Publication (DAS) No. 1,547,640, German Patent Application (OLS) No. 2,362,752, and the like. While these compounds have advantageous properties they also have some drawbacks. One drawback is the formation of a compound which causes stain. Such a compound is formed by the coupling reaction of the so-called non-color forming type coupling compound with the oxidation product of the color developer. Their most serious drawback, however, is the low reactivity of coupling compounds of this type with oxidation products of color developing agents. Accordingly, a large amount of these compounds must be employed because of their low reactivity and this results in a reduction in photographic characteristics and a decrease in shelf life. Further, all compounds disclosed in the above-described patent references yield mercapto group-containing compounds by reacting with the oxidation product of a developing agent. When compounds of this type are employed for producing a multilayer color photographic light-sensitive material, the resulting development inhibiting agent tends to remain in the layer to which such compound was added, i.e., it diffuses only with difficulty into other layers. Therefore, these compounds contribute only slightly to the so-called interlayer effect, resulting in unsatisfactory color correction.
In order to improve these drawbacks, a compound in which a triazole ring or a diazole ring is bonded to the coupling position through the nitrogen atom at the 1-position as described in Japanese Patent Application (OPI) No. 122,335/74 corresponding to U.S. Pat. No. 3,933,500 and German Patent Application (OLS) No. 2,414,006 is provided. While the photographic properties are improved to a certain extent using this approach, it is desirable from a practical standpoint to further improve these properties.